The invention relates generally to mounting system components and, more particularly, to mounting techniques to provide a desired structural condition of components through a range of operating temperatures.
Thermoelectric cooling devices (TEC) are well known in the art for removing heat generated from components, such as for removing heat from particular electronic components of a system. Specifically, solid state materials, such as bismath-telluride (Bi2Te3), may be provided a direct current to provide automatic temperature control, in accordance with the Peltier effect, to components in communication therewith.
For example, a TEC xe2x80x9cstack-upxe2x80x9d may be made in which a heat source component, such as may be a single component or a number of components disposed on a shared carrier, for which temperature control is desired is placed in contact with the cold side of a TEC and a heat absorbing or dissipating component, such as a heat sink or cold plate, is placed in contact with the hot side of the TEC. In order to ensure reliability of the TEC over a wide range of environmental conditions, it is desirable to maintain xe2x80x9cgentlexe2x80x9d compression to TEC elements. Specifically, the TEC elements are generally fragile under tension, and are stronger under compression, and therefore, a compression interface may be useful therewith to ensure good thermal interface in the stack-up. For example, a screw or similar fastener may be engaged in an orifice of the heat source component and the heat absorbing component to apply a compressive force to the TEC stack-up. Similarly, various types of clips may be engaged along an edge of the heat source component and the heat absorbing component to apply a compressive force to the TEC stack-up.
It should be appreciated, however, that the use of TECs is not without problems. For example, in order to provide uniform temperature control across a heat source component in contact with a single TEC and to ensure TEC reliability, a substantially uniform and constant compressive force should be maintained across the interface between the heat source component and the TEC and the heat absorbing component and the TEC. However, the use of fasteners and clips in the prior art has often resulted in nonuniform and/or varying compressive forces being applied, such as throughout a range of operating temperatures. For example, Bellcore sets forth performance criteria for systems utilized in the telecommunications industry requiring such systems to perform reliably throughout a wide range of operating temperatures, such as from xe2x88x9240xc2x0 C. to +125xc2x0 C., in which simple fastening systems of the prior art used with respect to heat source components comprising more than a single component or relatively small multiple component configuration will experience nonuniform and/or widely varying compressive forces.
Moreover, fasteners and clips utilized in the past are a source of heat leaking between the TEC cold surface and the TEC hot surface. Specifically, when conventional methods are utilized in providing clamping force to the TEC stack-up, a heat path is created from the hot side of the TEC to the cold side of the TEC resulting in a thermal loop. This thermal loop impinges on the TEC""s efficiency, thus reducing its usefulness in providing automatic temperature control with respect to the heat source component and/or heat absorbing component.
It should be appreciated that TECs are generally not structural elements. Specifically, although providing good compression characteristics, TECs generally are relatively weak with respect to tension or shear forces. Although such structural attributes are often acceptable when heat source and/or heat absorbing components exhibit a relatively small footprint, heat source and/or heat absorbing components having a relatively large foot print can result in excessive tension and/or shear forces being applied to a corresponding TEC of a TEC stack-up. For example, a relatively small TEC may be coupled to a heat source component having a relatively large footprint, such as an incoherently beam combined (IBC) LASER system, to provide cooling with respect to a localized source of heat. Accordingly, the heat source component may extend appreciably beyond the corresponding surface of the TEC, thereby resulting in tension and/or shear forces being exerted upon the TEC if a proper mounting configuration is not adopted and/or if uniform one predicted comparison is not maintained.
Moreover, the aforementioned performance criteria set forth by Bellcore with respect to systems utilized in the telecommunications industry may require such systems to perform reliably when exposed to dynamic forces, such as those of a physical shock and/or vibration. However, the center of gravity of the above described relatively large footprint heat source component may not correspond with the center of the TEC, further resulting in tension and/or shear forces when exposed to dynamic forces.
Accordingly, a need exists in the art for systems and methods which provide mounting structures for use with TEC stack-up configurations which provide substantially uniform and constant compression between the strata thereof, such as throughout a relatively wide range of operating temperatures. A further need exists in the art for such systems and methods to minimize heat leak such that a thermal loop is substantially minimized.
A still further need in the art exists for systems and methods which provide mounting structures for use with TEC stack-up configurations which provides a stable structural element adapted to withstand expected dynamic forces, such as those associated with a predicted level of physical shock and/or vibration. A further need exists in the art for such systems and methods to accommodate a relatively large disparity in footprint sizes of the strata thereof.
The present invention is directed to systems and methods which utilize mounting members adapted to provide consistent and/or predictable interfacing forces with respect to strata of a laminated structure, such as the heat source, TEC, and heat absorbing layers of a TEC stack-up, throughout a range of operating temperatures. Preferably, mounting members of the present invention are adapted to provide uniform compressive pressure across a surface area, particularly the Peltier elements of a TEC, to thereby provide a sound structure which is relatively resistant to dynamic forces and environmental variations. Preferred embodiment mounting members are adapted to minimize the transfer of thermal energy therethrough, such as to substantially minimize heat leak in a TEC stack-up configuration.
A preferred embodiment of the present invention utilizes a mounting member comprised of a material selected at least in part as a function of its coefficient of thermal expansion (CTE). According to a most preferred embodiment, a material from which a mounting member of the present invention is made is selected to have a CTE slightly higher than that of the effective CTE of a structure for which the mounting member is used to provide a compressive mount. For example, where a mounting member of the present invention is utilized in providing mounting of a TEC stack-up, the CTE of the mounting member is preferably selected to be slightly higher than the effective CTE of a corresponding portion of the TEC stack-up. That is, the CTE of a mounting member of the present invention is preferably selected to be slightly higher than that associated with the combination of materials utilized in the TEC stack-up between the points at which the mounting members are affixed to the TEC stack-up.
According to a preferred embodiment, mounting members of the present invention are fixed to a structure for which the mounting member is used to provide a compressive mount at a temperature outside of an expected range of temperatures associated with the expected operation of the structure. For example, mounting members of the present invention may be soldered, or otherwise substantially rigidly affixed, to components of a TEC stack-up while the entire structure is maintained at a temperature greater than the highest expected operating temperature of the structure. According to a most preferred embodiment, where the CTE of the mounting members is slightly higher than the effective CTE of the structure, a relatively constant xe2x80x9cgentlexe2x80x9d compressive force is maintained with respect to the structure throughout the operating temperature range after using the aforementioned higher mounting temperature.
Mounting members of the present invention are preferably adapted to provide structural support to a structure for which the mounting member is used to provide compressive mounting. For example, mounting members of the present invention may be provided with a relatively large diameter to thereby provide compressive, shear, and/or tensile strength to the completed structure.
Additionally or alternatively, mounting members of the present invention may be adapted to minimize stress associated with an interface between the mounting member itself and the structure to which it is mounted. For example, preferred embodiments of the present invention include expansion scores or cuts disposed at predetermined positions therein.
Preferred embodiment mounting members are adapted to minimize the conductance of thermal energy therethrough. Accordingly, the cross-sectional area of mounting members of the present invention is preferably minimized. For example, a most preferred embodiment of the present invention comprises a hollow cylinder to provide structural strength with minimum thermal conductance.
Accordingly, a technical advantage of the present invention is that mounting members of the invention may be used with structures, such as TEC stack-up configurations, to provide substantially uniform and constant compressive communication between strata thereof, such as throughout a relatively wide range of operating temperatures. A further technical advantage of preferred embodiments of the invention is that mounting members may be relied upon to provide structural integrity while minimizing conductance of thermal energy.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.